As is well-known, screw caps of containers, for example bottles, can be closed in rotary machines with several circumferentially arranged closers rotating about a common axle, the closing caps each being held in a closing head and rotated as well as lowered corresponding to the thread pitch after having been placed onto the respective bottle mouth. As an alternative, the containers can also be correspondingly lifted while the closing cap is being screwed on. The rotary motion of the closing head is here accomplished by means of an electric motor, and the lowering motion either by a control cam or by a linear motor.
In many applications, the containers are guided in the filling line and in the closer within a clean room to save agents for conservation, pasteurization, etc. on the one hand, and to be able to fill the containers with particularly germ-sensitive products on the other. Moreover, the containers and the products filled into it can be protected from leakages of the drive elements in such a clean room. To further reduce the amount of germs and soiling in the clean room, as many components of the closer as possible are disposed outside the clean room.
For this purpose, EP 2 221 272 A2 discloses a device for closing containers by contactless torque generation. Here, a rotary machine with several closers is disclosed, where each torque of a motor disposed outside a clean room is transmitted contactlessly to a closing head within the clean room by means of a magnetic coupling. The lifting motion of the closing heads is here effected via a control cam within the clean room.
Analogously, WO 2010/118806 discloses a closer for screw caps or closures where a drive is hermetically separated from the closing head by a magnetic coupling.
This has the disadvantage that such magnetic couplings involve a corresponding cost factor and that the magnetic couplings must be dimensioned to be correspondingly large for transmitting the required forces, and thus the masses to be moved have disadvantageous effects on the drive system.